That card is Physically too Long AND the power supply in 9020 DOES NOT SUPPORT that card.

EVGA 700BR is ok but requires an adapter to work.

https://www.amazon.co.uk/EVGA-100-BR-0700-K3-Bronze-Power-Supply/dp/B07G6683R5/

Short Cards Like the ZOTAC MINI are fine.

https://www.zotac.com/us/product/graphics_card/zotac-geforce-gtx-1060-mini

https://www.amazon.co.uk/gp/offer-listing/B01IA9FEOO/ref=dp_olp_0?ie=UTF8&condition=all

Optional 365W power supply works or you need an adapter from Moddiy.

You can get a 365W power supply and a Short GTX 1050 TI or even 1060.  For Non Dell video cards WILL HAVE to turn SECURE BOOT OFF.  When installing an after-market graphics card into a Windows PC with UEFI secure boot enabled, the system may not boot.  This is true for ANY PC not just Dell.  Only short cards 8.5 inches or less fit into the 9020 case.

http://nvidia.custhelp.com/app/answers/detail/a_id/3156

Dell OEM full height but short PCI-E video cards work 

365w PSU =
7VK45 365w, Huntkey
T1M43 365w, Delta

DVP9W Nvidia GeForce GTX 1050 Ti,  4GB, 75w
36V90 Nvidia GeForce GTX 1060, 3GB, 120w
24K8H Nvidia GeForce GTX 1050,  2GB 75w
8CCF1 Nvidia GeForce GT 1030, 30w
1MPR3 AMD R9-360 2GB, 75w
24K8H Nvidia GTX 1050 2GB, 75w

BARE Minimum working is Specific EVGA 750B1 or 700B1

100-B1-0700-K1

https://www.amazon.com/EVGA-BRONZE-Warranty-Tester-100-B1-0700-K1/dp/B018JYHBE6/

The 24 pin power supply connector is 8 pins.  The proprietary power supply only has 12v rails.   The only way you get the evga power supply working is with an adapter from MODDIY CAB359.

https://www.moddiy.com/products/Dell-OptiPlex-9020-PSU-Main-Power-24%252dPin-to-8%252dPin-Adapter-Ca...

Power supplies that have problems from 350W all the way thru 850W issues are due to INSUFFICIENT power on the 3.3v/5v rails. 

There's also a guy who made his own adapter.
https://raphtec.wordpress.com/projects/dell-poweredge-t20-atx-power-supply-adapter/