- Edited
treequell I'll suggest installing Molly from Accrescent IMHO (if you don't have Play Store), it's more secure and you don't have to TOFU because apps are verified before installation. It's a bit out of scope though.
pdagenius
If you have downloaded Signal from the website (meaning the apk) I'll suggest to you to let Signal updating itself when there's an update available. If you installed it from Aurora, just use update Signal via Aurora then.