What are some best practices for setting up Google UAC campaigns?

Be sure to maximize your creatives and copy inside the adsets (else Google creates them for you). AEO works well so link up any key events directly from your 3rd-party MMP source.

Other things I've seen that work well are splitting up campaigns with large daily budgets into several smaller ones (even when identical). So for example rather have 3 campaigns with $1000 daily budget instead of 1 campaign with $3000 daily budget. And for location based targeting; for most apps it's best practice to only target people who 'live' in the location (under advanced location settings in your campaign) rather than targeting people passing through your target location like tourists etc. unless that's your audience ofc.

Obvious but good to remember: a lot of things in UAC are based on your Play Store presence (keywords are taken from your app description by the algorithm etc.). Screenshots and other elements from your page are also used by Google to automatically craft creatives for UAC (even your app's header image). So it's just good to take UAC into account when doing ASO in general.

UAC for iOS works the same way as Android, but you'll have to rely mostly on display traffic and generally a much smaller inventory. Search placements are limited as I believe Safari searches are blocked for the most part (unless someone uses the Chrome app as a browser on iOS). Also, some of UAC's placements on Android are displayed directly in the Play Store. Google obviously can't provide that for iOS (Apple's ASA). Another thing to check in the MMP settings, is that by default UAC calculates conversions as 'store downloads' from their direct connection to your Google Play Store account. Whereas for iOS your installs would be 'first-app-open'. This is one to align when you run both iOS and Android UAC campaigns on the same accounts, so that you're comparing apples with apples.