Unfortunately, we do not hand out APKs individually.
As an alternative to Google Play Store, you can also try to download spacedesk for Android from the Amazon Store.
Download link to Amazon Store is available on our website’s download page – https://forum.spacedesk.net#download.
I have a similar problem.
I have a discontinued tablet that I can’t install apps with the play store and amazon.de doesn’t let me get the app because of “geographical restrictions”.
If I could try installing with the apk file maybe I could save that tablet.