Solution
NI TSN (Time Sensitive Networking) devices are IEEE 802.1AS compliant devices designed to be synchronized on the hardware level. If your devices are not both 802.1AS-compliant, they can't be synchronized with TSN. An option you have to sync the devices is over software with IEEE 1588-2008 Software Timing using NI-TimeSync. Have a look at
Using NI-TimeSync to Configure IEEE 1588 and 802.1AS Time References for a detailed description on how to do this. Note that this only synchronizes the Real-Time clocks (not FPGA), and synchronizes with an accuracy of 1 ms, whereas TSN has an accuracy of 1 us or less.
Furthermore, it is worth noting that when you design a network based on NI TSN, all devices in the synchronization chain must explicitly support IEEE 802.1AS. That also includes network switches and media converters.