I want to make a website using GitHub Pages but can I get FTP access for the website?
No it's not possible. GitHub Pages is for intended for Git users and projects, it is not intended for people looking for a free web host. To use GitHub you must use a GIT compatible client or the terminal.
If you want to host your website on GIT then you need to add a repository and upload your files using
git commit and
git push, then once you have uploaded your repository you then need to clone it to GitHub Pages like so:
git clone https://github.com/username/username.github.io