I can’t upload files

Usually, this happens if your server has some limits that prevent Filr from uploading files. You should have a look at Filr -> Settings -> Status – scroll down to the “Server Settings” section and double-check everything looks fine and there are no errors:

I can't upload files 1

Filr uses the configured upload size of WordPress. So if you want to upload larger files you can try to increase that from the .htaccess file or a custom php.ini file as explained here.