Revoice Pro 4 will not show up on the new Plugins page, but can be found in this legacy installers article instead:
https://synchroarts.zendesk.com/hc/en-us/articles/22319520396055-Synchro-Arts-Legacy-Installers
Connecting an iLok ID with a valid/full Revoice Pro 4 license will unlock upgrade and crossgrade pricing:
https://synchroarts.zendesk.com/hc/en-us/articles/23294434628119-How-do-I-receive-upgrade-or-crossgrade-pricing
If your discounts do not show up right away after connecting your iLok ID, please wait a few minute, clear your browser's cache, and reload the Plugins page.