How do you remove the “The Link You Followed Has Expired” error for a subfolder website?

I am building a wordpress website in a subfolder of a drupal website. I want to add a new theme by uploading a theme file but I keep getting the “The Link You Followed Has Expired” error. From my understanding, this error is a configuration issue. I need to increase the maximum upload file size. However, no matter what I try, it does not work. Here is what I have tried so far :

1/ Add the following lines to the .htaccess of the subfolder website :

php_value upload_max_filesize 128M
php_value post_max_size 128M
php_value max_execution_time 300
php_value max_input_time 300

Unfortunately, when I do this, I cannot reach the subfolder website anymore. I always end up on the root website's welcome page instead.

2/ Create a php.ini in the subfolder with the following lines :

upload_max_filesize = 64M
post_max_size = 64M
max_execution_time = 300

That did not change anything. I still have the limitation and the error (sorry it is in French) :

I called phpinfo in the subfolder and the upload limit seems to be set properly so that is a little weird. This is what I get with the php.ini file in the subfolder.

If possible, I would really like to avoid modifying anything in the root website. Could you please help me?