Hi,
thanks for your great product!
I am developing some apps (well, more 'learning to develop' at the moment 😉 ), and at least a few weeks ago, the following worked for me:
- compile .apk file on my windows laptop
- copy .apk file to dropbox-folder on laptop
- open dropbox-folder on my android-10 smartphone
- click on .apk file on android
- click yes on permission-questions if needed
- open my new application on android
I have given Dropbox permission to install unknown apps. Everything worked fine!
However, a few days ago, I had to upgrade Android(security patch level 2020-05-01). Dropbox was upgraded as well (now on 188.2.6). If I now click on .apk file, I get the following error:
 Unable to Send
 Your account admin has placed restrictions on sending files of certain types.
See attched image.

Please advice!
Thanks, Steven de Brouwer