Thanks DonManfred, that helped a lot.
For future reference for others also with this issue (and to save a lot of time), I followed Erel's article
here.
Initially I only installed Android SDK Platform 35, but ran into a compile error:
aapt2.exe E 07-03 12:22:32 18036 20212 LoadedArsc.cpp:94] RES_TABLE_TYPE_TYPE entry offsets overlap actual entry data.
aapt2.exe E 07-03 12:22:32 18036 20212 ApkAssets.cpp:149] Failed to load resources table in APK 'C:\Android\platforms\android-35\android.jar'.
Upgrading OpenJDK, AndroidSDK Command Line Tools, and Required Resources did not solve it.
I ended up deleting C:\Java, C:\Android, and uninstalling B4a, then following the initial setup instructions
here.
Then download Android SDK Platform 35 via B4A SDK Manager then update paths via Configure Paths. Issue resolved.