When do I need bridge ?

I was wondering if I need to purchase the bridge device ?

I have on order the doorbell pro and also security flood with camera. I also already have the Schlage electronic door locks with zwave. I read that I need a hub for those and I was wondering if the ring bridge would handle that.

If you are talking about the Ring Bridge, that is for Ring lighting control - which it does not sound like you have.

I thought I might need it to get my smart locks to talk with ring and Alexa

Usually the smart Lock needs a hub of it’s own to talk with Alexa. The Ring hub won’t do that.

Have you seen our Bridge article @KSutton ? Learn more, here: https://community.ring.com/t5/Smart-Lighting/How-it-Works-Smart-Lights-Bridge/m-p/6026#M282