BottraDevil

I see a guy in reddit post this by the name Budget_Material2076 and it work for me I know how to fix this on Mac. Go into the mail app , click mail then preferences , after on the bottom left hand corner you will see Manage plugins, click Sideloadly and make sure its check, it will close and restart the mail app. then open Sideloadly and install the app. Your welcome guys 😃 to make it super clear how to do it Open Mail application>Prefences>general (find the manage plugin button on the left corner)>able sideloadly