Ensure CRM and Subscriptions are integrated by going to CRM settings > Marketplace > Zoho:
If you have integrated Zoho Finance Suite, you can find the details by clicking on 'Manage' under the Zoho Finance Suite.
Ensure all modules are properly synced. To view the field settings, click on the settings icon on the right hand side (Visible when you hover your mouse on a section; seen below for the Vendors module.)
Please note that in order to enable payment gateway in the plugin, your payment gateways should be integrated in Subscriptions. To confirm this, go to Subscriptions Settings > Integrations.
Back in the plugin setup go to Zoho API settings. Follow the instructions on the page.
If you have multiple organizations tied to your Subscriptions account, make sure you are inputting the right id. You can see all the organization ids, when you click on the profile pic on the top right.
For customizing the Subscriptions tab for the front end user, navigate to the Customization > Zoho Subscriptions and follow the instructions for each section.
For general definitions, refer to the 'Customization and Layout' documentation