You could possibly use the following tutorials to determine your wireless password. Some wireless routers may have this printed on a sticker affixed to the device if you are renting them from your ISP. Additionally, if you are renting the equipment your ISP tech support would be able to assist with this if you call them.
Determine your wireless password, Windows 10 – https://support.microsoft.com/en-us/help/4023501/windows-find-wireless-network-password
Determine your wireless password, Mac OSX – https://www.softwarehow.com/find-wifi-password-mac/