Use the plug in role scooper.
If u are trying to upload more file types than is possible and u get the sign this file is not permited or sometnig like this.
Go to ur file system.
wp-includes click on functions.php
Search for the function wp_get_mime_types
search the mime extension in this list:
https://www.webmaster-toolkit.com/mime-types.shtml
And than simply add the file type.
Dont use the . thats in the site’s structure.
like this:
‘gif’ => ‘image/gif’,