Go to your cloudflare dashboard, open Storage & databases and click on Overview

On the right under Account Details click on the manage button for API Tokens

Create a new Account API Token

Set the name, permissions, bucket limitiations and any IPs you want to bind it to

Make note of the Access Key ID and Secret Access Key

the URL at the bottom will be required for the endpoint field at the end of the config creation

rclone config
n
R2
s3
Cloudflare
false
<access_key_id>
<secret_access_key>
auto
<endpoint>/bucket-name

Once done you might want to go into the rclone.conf and add acl = private to the end of the remote