Dell Rewards

https://www.dell.com/en-us/lp/dell-rewards

I still don't see my rewards for the purchased laptop 

Obviously you did not read the link I posted.  If you followed the instructions and made purchase using the same email with your Dell Reward account, you will see your reward within 30 days. 

Thanks, Chino de Oro!

I still have a question.

I ordered my laptop 31 May 2024

But it looks like I joined the reward program 01 June 2024 (received my welcome Dell rewards).

In the FAQ:

"Can I receive points on Dell purchases placed prior to enrolling in the Dell Rewards Program?

No. Dell Rewards points and other program benefits will only apply to purchases placed at the time of or after program enrollment."

Will I get my rewards in this situation?

Or should I buy the laptop again, get the points and when I receive another laptop, send it back as a return?

It was quite unclear that I won't get the points automatically...

In my personal opinion, Dell reward points is not worth that much of your effort to go through all the hoops.  After all, you must buy Dell products with your reward, a marketing strategy to entice customers spendings. 

Of course, you are entitled to your own choices.  If the purchase was made prior to your setting up Dell Reward account, it would not be qualified for reward points.  Cancelling current order and placing new order may creating some issue along the way.  You must be careful with the process.