for those of you having trouble doing this, I was able to figure it out and these are the steps I took. 

1. In podio, downloaded rei leads app under my work space
2. Went to the app settings (wrench icon)
3. Select "email to app"
4. Choose the gmail icon on the "choose your email service"
5. Sign into your google account
4. Grant podio access to the information requested
5. Go back to the app settings menu and you should see your google account there, select "add to this"
6. Now copy the email address at the BOTTOM of the screen.
7. Log into your google voice account and go into your settings (gear icon)
8. Select the voicemail & texts tab
9. Select add email address
10. Paste the long email address you copied from podio (you will get a notice from google that they sent you an email to try and verify that email address)
11. Go back to podio and hit the refresh button on your browser
12. Now on the rei leads app ( or whatever app you are trying to link) there should be a new entry
13. Select that new entry and you will see that it is an email from google with a link to verify the podio email address
14. Right click the link and select "open in new window"
15. Type your google password
16. You will now get forwarded to a message from google that says the (podio) email address has been verified
17. Your good to go

FYI if you have multiple google voice numbers you can't link them into a single app, download another rei leads app or whatever you are using to capture leads and change the name of the app (by going into the app settings) and follow the same procedure to add another google voice number to this new app

Hope this helps!