I suggest you pick a longer time control. You can try 15/10 (which is 15 minutes per player plus 10 seconds added to the clock on each move) or 45/45 (45 minutes per player and 45 seconds added each move). That should solve the clock problem.
I have solved a lot of puzzles on chess.com and have not found any to violate the rules of chess in any way. Sometimes you do have to sac a queen or some other valuable piece in the puzzles, but always for a good reason. You always end up either check mating or winning material in the puzzles.
I've been a member of Chess.com for just over a year. I didn't want to start by playing other humans on-line until I took the time to understand the basics. I figured that by playing bots and puzzles I could make mistakes without causing human players to suffer with my admitted incompetence. My chess time has been about 60% puzzles and 35% computer bots - and only recently, 10 minute games against human opponents on Chess.com making-up the remaining 5%. PUZZLES: I play puzzles on two websites; chess.com and lichess.org. I've played over 5,000 puzzles on chess.com and about half that number on lichess.org. In my humble opinion the puzzles on lichess.org are significantly better than chess.com. For starters, the "rated" puzzles (blue icon) on chess.com contain frequent errors - I've saved dozens of puzzles that are either laughably wrong or even violate the rules of chess (see one sample of what the computer thought was the "correct" move, below) I have problems staying near my peak puzzle rating of 1398 because by my estimation roughly one in six puzzles are 1) stupidly wrong or 2) give away high value pieces for no perceivable gain or 3) violate the rules of chess. I have yet to find a puzzle on lichess.org that violates the rules of chess and my rating is slowly improving into the 1400 area. BOTS: I have played several hundred games against BOTS. Note that these games are played without a clock so I can take all the time I want to consider my next move(s) - this turns out to be a HUGE advantage which I do not enjoy in the timed games I play against human opponents. I beat BOTS rated 600 and under roughly 90% of the games, roughly two out of three for BOTS between 600 and 1000, one out of four or five for BOTS between 1000 and 1400 (Nelson BOT) and have only beaten a BOT over 1400 twice (Mateo BOT). As far as playing human opponents in timed (10 minute) games, of the roughly 20 games I have played I don't do well, even though no one I have played is rated over 400. The two reasons I attribute this lack of dominance over low rated players are the 10 minute clock is entirely new to me and sometimes I lose on time and the approach to the game exhibited by newer players is unfamiliar to me as compared to higher rated BOT players I play. And yes, just to check I played BOT Juan (400) and dispatched him rapidly - but I still lose to human players in the 300 range. However my BIG frustration is the lack of face-to-face contact with other, more experienced chess players. Largely because of covid all the chess clubs here near the Illinois-Wisconsin border have been inactive for a long time. I was excited to see a local community college offer a chess class - but it too was canceled. I even got the contact info for the instructor and sent him an email - but no response. I would be grateful if you would share your experiences in your approach to chess by adding to this topic. Thank You!