The theme is not installed

The theme is not installed

Hi.
I bought the theme (CarDealer) because it seemed like a good option, the problem arises when installing the theme in wordpress when I get the following message:

Warning: POST Content-Length of 8515897 bytes exceeds the limit of 8388608 bytes in Unknown on line 0
The link you have followed has expired.
Please try again.

I add a file with screenshots.
If someone could help me with this problem.