ComTac is not a public app. It is distributed to a closed list of operators, and Google Play only shows it to the exact Google account your invitation was sent to.
Open the Play Store app, tap your profile picture in the top-right corner, and check which Google account is active.
It must be the address your ComTac invitation was sent to. If a different account is shown, tap it and switch. If you install while the wrong account is active, Google Play shows a blank white page, "item not found", or "not available in your country" — because to that account, ComTac does not exist.
1. Confirm the Google account, as above.
2. Open this on your phone:
OPEN COMTAC IN GOOGLE PLAYhttps://play.google.com/store/apps/details?id=com.comtac.app
3. Tap Install.
4. Open ComTac and sign in with your invitation email address and the password you chose during registration.
If step 2 shows nothing useful — use the web opt-in instead. Copy the address below and paste it into Chrome (not the Play Store app), signed in with the invited account, then tap Become a tester:
https://play.google.com/apps/testing/com.comtac.app
Almost always the wrong Google account. Play Store → profile picture → switch to the invited address, then retry. If it is still blank, the link was opened inside the Play Store's built-in browser — paste it into Chrome instead.
Same cause: the active Google account is not the invited one. If the account is definitely correct, wait a few hours — new access can take a while to propagate across Google's servers — then try again.
That is fine, but ComTac installs only under the invited account. Make it the active Play Store account before installing, and keep it active when updating. The app itself is available to every profile on the phone once installed.
Your access is registered under your invitation address exactly as written. An alias, a "+" variant, or a work address that forwards to your Gmail will not match. Reply to your welcome email telling us which Google account you want to use and we will add it.
Uninstall that copy first, then install from Google Play. Google Play cannot update an app it did not install, so you would silently stay on an old version.
Check you have not left the tester programme, and that the active Play account is still the invited one. New builds normally reach phones about an hour after we release them. Play Store → profile picture → Manage apps & device → Update available.
Forget the device in Android's Bluetooth settings, power-cycle the node, then retry from inside ComTac. Enter your PIN if prompted. If no PIN dialog ever appears, tell your administrator — the node needs reconfiguring over USB.
Your ComTac sign-in is separate from your Google account. It is your invitation email address plus the password you chose at registration — not your Google password.
Yes. Please do not opt out from Google Play — it interrupts your access and resets your enrolment. If you want to stop testing, tell us instead and we will handle it.
Reply to your ComTac welcome email with a screenshot and the Google account you are using. We answer every one.