My professional background is backend engineering, but I volunteered to help a nonprofit, and their website runs on wordpress, so I wrote some php that solves a problem for them, which I tested by running locally (via https://localwp.com/).
I had planned to get this code onto their live website, and recommendations that I've found online suggest uploading the php via ftp, using it to create a new template, and making a wordpress page using that template.
My problem is that the nonprofit I'm talking to doesn't know much about their wordpress instance, and their webmaster has been very noncommunicative, and I'm not sure how much he knows about wordpress beyond what he can access in the admin UI.
Besides FTP uploading, what options do I have to implement custom php in a wordpress site? I have an admin login.
Sorry to be verbose, thanks in advance!
If you have the WordPress login details, you can use the File Manager plugin to upload the files. But it's a little unsafe because if something goes wrong the website might go down so you need FTP login details to fix it. I recommend requesting them to give you Cpanel login details or their hosting login details to upload all your files via Cpanel.