most likely your FTP user is a system user on your linux, so just change the password:

passwd username

ie: passwd ftpuser1

Also you should try to use SFTP, FTP is old, unsecure and ugly

Hello, @dianetemple824

By default, SFTP uses the SSH protocol to authenticate and establish a secure connection. Because of this, the same authentication methods are available that are present in SSH.

You can use the root username and password in order to access your droplet using sFTP. If you’re unable to access the droplet using the ssh you can also reset your password.

Although passwords are easy to use and set up by default, we recommend you create SSH keys and transfer your public key to any system that you need to access. This is much more secure and can save you time in the long run.

Please see this guide to set up SSH keys in order to access your server if you have not done so already.

If you can connect to the machine using SSH, then you have completed all of the necessary requirements necessary to use SFTP to manage files. Test SSH access with the following command:

ssh sammy@your_server_ip_or_remote_hostname

You can check these two tutorials:

https://www.digitalocean.com/community/tutorials/how-to-use-sftp-to-securely-transfer-files-with-a-remote-server

https://www.digitalocean.com/docs/droplets/how-to/transfer-files/

Hope that this helps!
Regards,
Alex