To set up guaranteed rent, you will need to create a service type as it will process rents very different to a standard managed rent. Please go to your service types section which is located
Small person icon in the top tight > Object Types > Service Types > Add in the top right
...and create a service type (please see the guide for "service types" for further guidance) - to make the service type specific to guaranteed rent, please slide the switch for guaranteed rent on your newly created service type.
You can also set a fee here as you'll see above - this will serve similarly to a management fee in that when the rent reaches the landlord, it will apply an automatic charge of your chosen value i.e. a percent of the rent or a fixed amount.
When this service type is applied to any tenancy, it adds a new sub account against the tenant called guaranteed rent, into which money will flow over from tenant main on rent due day so that it can automatically move from there to the landlord account - this ensures that the landlord will not be waiting for tenants to pay their rent, but rather have security in receiving rent on a specific date regardless or whether or not the funds were paid by tenant. It will also be clear from here whether a tenant is in arrears to you as there will show a negative balance in the main of the value they owe you.
Take a look at this rent to rent guide as well for an alternative method known as rent to rent which some agents adopt - https://letmc.zendesk.com/hc/en-us/articles/360018806211-Rent-to-Rent