[Question] Learning basics

[gc-ss]

Just discovered this awesome project. Questions:

0. This repo is the frontend UI for the backend at https://github.com/forwardemail/free-email-forwarding ?

I'm attempting to self host and get the following error when deploying:

MISSING CONFIG VALUES: PAYPAL_WEBHOOK_ID, PAYPAL_ENHANCED_PLAN_30D, PAYPAL_ENHANCED_PLAN_60D, PAYPAL_ENHANCED_PLAN_90D, PAYPAL_ENHANCED_PLAN_180D, PAYPAL_ENHANCED_PLAN_1Y, PAYPAL_TEAM_PLAN_30D, PAYPAL_TEAM_PLAN_60D, PAYPAL_TEAM_PLAN_90D, PAYPAL_TEAM_PLAN_180D, PAYPAL_TEAM_PLAN_1Y, PAYPAL_CLIENT_ID, PAYPAL_SECRET, STRIPE_PUBLISHABLE_KEY, STRIPE_SECRET_KEY, STRIPE_ENDPOINT_SECRET

1. Should I just populate these with an empty string ("") or perhaps a string like "NA" (this is for internal use only and I don't plan to resell the service/need paying customers)?
2. Or will attempting to do so lead to failures down the line because the PAYPAL and STRIPE modules will attempt to validate these config values once the server comes up?