Firmware 3.x on the GL-iNet router does export the configuration file with the Public IP address, not the private IP address. Firmware 4.x also exports the Public IP address, but allows you to choose to export the DDNS domain name.

It looks like the following statement is reversed, but, interestingly, the graphics are correct (attention: @alzhao):

2. Edit the configuration to replace DDNS url with your public IP address.

The OP is currently using the Public IP address 70.77.7.32 and, once VPN is at least working, should switch to using DDNS (no harm whether or not the 70.77.7.32 is dynamic or dedicated).