The 718 Owners Manual specifically states that to take advantage of the smartphone-integration features of BOTH Porsche Connect and Porsche Connect Plus, the USB port in the center console must be used. On 718s, the USB port in the glove box is only good for (very slow) device charging, iPod integration, and for data transfer to PCM4; it is not enabled for smartphone integration.
This page in the online 718 manual should help clarify things, and lead to other parts of the manual that talk about the PCM system in general:
Page 58 | 2017 718 Cayman Manual | Porsche iManuals
This page in the online 718 manual should help clarify things, and lead to other parts of the manual that talk about the PCM system in general:
Page 58 | 2017 718 Cayman Manual | Porsche iManuals