The sender needs a country that matches where that LinkedIn account lives. Owner or admin assigns it on the Proxy tab, saves, then connects.
Assign the country, then save
The Proxy tab is required before Connect to LinkedIn. If the country is missing, the panel says "Assign a country proxy in the Proxy tab, then save."
Sign in as Owner or admin.
Open the sender and select the Proxy tab.
Choose Managed country. That is the path we recommend.
Pick the country that matches where this LinkedIn account lives, then save.
Wait until the panel is ready, then return to LinkedIn and select Connect to LinkedIn.
Managed country and Custom proxy are the two modes on that tab. Custom proxy is a separate choice. Stay on Managed country unless you already decided to use that later path.
Do not paste a host, port, or password for the managed path. Do not name a vendor. The country is the only choice you need.
If connect still asks for a country
Save again on the Proxy tab, then connect. Changing country later releases the current assignment and pauses LinkedIn until you reconnect. Assign the country before you add a second sender.