Decided that i want to play Terraria on mobile since I heard about the parity update. Disappointed to be facing the same issue as OP.
Should anyone facing the same problem, I recommend trying to install Terraria using Aurora Store. It is an alternative Play store frontend and it is not a warez store. Logging into your Google account allows you access to download Terraria should you already bought it.
NOTE: There's a disclaimer that there is a possible account termination if you sign into the app due to Aurora Store is in violation of Play Store's [old] ToS (latest terms however show no explicit violation). So far I have not being banned and I indeed is using my main Google account. I also have used this tool for 2+ years. But of course, i must inform you of the risks.
DOES THIS JUSTIFIES 505GAMES OR RE-LOGIC TO CONTINUE LOCKING THE GAME FROM LEGITIMATE CUSTOMERS?
After many empty promises for this to be looked into in myriad of threads reporting this problem — a big hard NO. Users should not need to use alternative platforms in order to install and play the product that they purchase with legitimate means. The inaction of the issue could make desperate users use malicious APKs online instead just to play the game that they have legitimately bought. As a Terraria player since 1.1 launch on PC, i am very very disappointed with the lack of attention and resolve for this.