Yes, the Nikon Z6 III is compatible with the Transcend 700S V90 64GB.
Transcend 700S's manufacturer-rated write speed is 180 MB/s. Nikon Z6 III's own product page recommends an SD card sustaining at least 250 MB/s for 4K60/high frame-size/rate recording (a raw benchmark floor, not just a V90 class label -- this camera is a documented exception to the V-class-is-authoritative rule). 180 MB/s falls short of that 250 MB/s figure by 70 MB/s, despite carrying a valid V90 class rating (V90 only guarantees 90 MB/s sustained, not 250). The camera's standard 4K30 mode only needs 45 MB/s, which this card clears with wide margin.
Limitation
Cannot reliably record 4K60 -- Nikon's manual recommends an SD card sustaining at least 250 MB/s for that mode, and this card is rated at 180 MB/s (V90's class guarantee is only 90 MB/s sustained, well short of Nikon's recommended figure here). Works for 4K30 and standard video recording.
“CFexpress or XQD cards with a maximum data transfer rate of at least 250 MB/s, or UHS Speed Class 3 or better SD cards with a maximum data transfer rate of at least 250 MB/s, are recommended for recording and playback of videos with a high frame size or rate.”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)