Hopefully the author sees this and adds it to the list, since this is the top google result. There is also a -504, which this article actually seems to be addressing instead of the actual 504.
You might receive an error that contains random numbers when you download Office apps from the Google Play store. The Google Play team is aware of this problem and is working to resolve the issues. In the meantime, please see below for more information and try the workarounds suggested.
What are Google Play Store errors?
Google Play Store Errors typically contain random numbers and are generated when you try to download apps from the Google Play Store. These errors might be due to Google Play Store updates, Google cache issues, Google Play Store stored data issues, or Google account issues.
The following are some of the most common Google Play Store errors:
Google Play Store error code 18
Google Play Store error code 20
Google Play Store error code 103
Google Play Store error code 194
Google Play Store error code 492
Google Play Store error code 495
Google Play Store error code 505
Google Play Store error code 506
Google Play Store error code 509
Google Play Store error code 905
Resolve Google Play Store Errors
Try the following workarounds to fix the Google Play Store errors.
Clear the Google Play Store cache
Open the Settings menu on your device.
Go to Apps or Application Manager. (This option might differ depending on your device.)
Scroll to All apps and then scroll down to the Google Play Store app.
Open the app details and tap the Force stop button.
Tap the Clear cache button.
Repeat the steps above, but replace Google Play Store in step 3 with Google Play services.
Try to download the app again.
Clear the Google Play Store data
If cleaning the cache of the Google Play Store and Google Play Services doesn't resolve the issue, try clearing the Google Play Store data:
Open the Settings menu on your device.
Go to Apps or Application Manager. (This option might differ depending on your device.)
Scroll to All apps and then scroll down to the Google Play Store app.
Open the app details and tap the Force stop button.
Tap the Clear data button.
When the cache and data are cleared, the Google Play Store error should be resolved. If not, continue to the next step.
Remove your Google account and then add it again
If clearing the cache and data doesn't resolve the issue, remove your Google account, restart your device, and then add your Google account again.
Open the Settings menu on your device.
Under Accounts, tap the name of the account that you want to remove. If you're using a Google account, tap Google and then the account.
Tap the Menu icon on the top right corner of the screen.
Tap Remove account.
Restart your device and add your account again. Then try to download the app.
Additional help
If these steps don't resolve the error, refer to the following:
Part 1: Reasons for Google Play error 505
As per the report by some users, error 505 occurs in certain apps such as Weather App, SBI, ITV, Adobe Air 15, We Chat etc.
To have the right idea about the problem, we have listed all the reasons of it occurrence below:
a. Google play store is not updated or refreshed (Causes the error during the downloading process)
b. Due to installation of an outdated version (In case your Android version is outdated may result in error in the installation process)
c. Cache memory(Is the redundant data occurs due to search history)
d. Application is not compatible with the Android OS (If the app you are downloading is not the updated may cause error)
e. Sync error in Google account(Google Account is not properly synchronized with the data of your device)
f. Adobe air app
g. Data crash (Many time app or Google play store crashed crashes after downloading it, reason may be some bugs, so many apps are open, less memory etc.)
Now that we know the reasons, let us also learn about the solutions that will guide you to resolve the error code 505.