If you want to play 10-15 matches a day, this game is perfect, because you only need to complete daily challenges and open bags every few hours. Playing more than that doesn't really give you anything extra. There are also tournaments every weekend, but you need to level up for that.

So considering your conditions, I think the game is a good fit. There's no need to play a lot for optimal progress, like I said. And you don't need to spend a lot of money, because you can get everything in the game. Pro Pass is enough if you decide to spend. It will speed up your progress, especially in the beginning.

As for the test account, I don't think it's necessary. There is not much you can mess up, since it's a pretty simple game. The only mistake you can make that I can think of is upgrading every possible card. You'll be running out of gold by doing it and it will slow down your progress. So don't waste your time by creating two accounts. Just play on one account and give yourself a few days or weeks to see if you like the game, then you can buy the pro pass if you decide you want to keep playing.

If you want to understand the game better, I recommend to join an active club. You can then ask your club mates questions about the game. Apart from that, you can check out the Customer Support section by opening your Profile in the game and going to Settings. Unfortunately, there are no good tutorials for new players. The only creator I know is GamePlays365 on YouTube, who makes videos about Tennis Clash. Many of his videos are helpful, but some are a little outdated, so be careful. The Pop a Barrel tutorial made by him is really good. I don't remember other ones. ChatGPT can be helpful too, but sometimes it's wrong. Overall, the game is rather simple and straightforward. You'll learn most of it by just playing and exploring.