Grace Transferwise integration is only included with the various Premium memberships. But the Transferwise integration is only relevant for outgoing transfers anyway. It has nothing to do with how incoming payments are handled, and even if it wouldn‘t be there (like with the old Free memberships), the customer could just go to the Transferwise website manually and access the same functionality without any changes in fees.
Anyway: If you want to receive a transfer internationally, most of the time the cheapest and fastest option is for the sender of the payment to just use the Transferwise website themselves and send the money to your account. That would also work with the Travel Card IBAN then, as the money will then go through Transferwise and you would receive it like a regular SEPA transfer. (Of course, other third party services can also be used like this, Transferwise is just an example. In most cases I think they are superior to their competitors, though.)
If you can’t or don’t want to go with a 3rd party: With any of the Premium subscriptions, it‘s also possible to receive SWIFT transfers from world-wide, as long as they‘re denominated in Euros (any other currency transaction will be rejected). These always incur additional fees for receiving (at least 5€, for more info look at the pricing document on bunq.com*), though, and I‘m not actually sure if they‘re also available for the Travel Card membership. Maybe it could work, but I can‘t find confirmation of this 😕 Maybe you could ask Support for confirmation if this type of transfer can be received on a Travel Card membership. In any case, this would probably be one of the more expensive options and sometimes it may not be possible for the sender‘s bank to send Euros directly to bunq. (Going through an intermediate bank is sadly not an option and won‘t work.)
I hope that helped and wasn‘t too confusing 😁