Hi SMAdmin
I'm sorry but it's not possible to send an APK.
Anyway, you don't need to change any account to install the APP through Google Play as the accounts aren't linked to SML when you install it. You can join the beta testing group with any Google Play account and install the APP and, once installed, you can log in using your Stock Management Labs account.
I hope this helps.
Best Regards,
Salva.