File uploading error

[ChrisPAR]

@Nehaal

But when I upload larger files like 40 MB or even 20 MB, it says “There was an error uploading your file”.

This is intended behaviour:

What is the file/upload size limit

On all InfinityFree servers is a file size limit of 10 MB. It’s important to note that this is a file size limit and not an upload limit. The difference is subtle, but important. An upload limit could be set through PHP settings, but this limit is enforced on the file system level. No PHP configuration can override this limit and it applies to files uploaded through FTP or the file manager as well. Can the limit be increased? No. The size limit is fixed and cannot be increased in any way. 10 M…

@Nehaal

a site where users signup and can upload files

Please note that InfinityFree is a web hosting service, not a file hosting one.
In addition to the file size limit which will make running such a service hard, hosting it also violates the Terms of Service, section 5 (emphasis my own), and will get your website suspended:

You agree to not use the Services to:
upload, post, email, transmit or otherwise make available any material that is of keylogging / proxy service / irc / shell(s) if any type / file hosting / file sharing types.