Summary:
1. if you see blank or empty for connector field, you will automatically know these 3 connector will be use(and,at,&)
space is never going to be a connector ( unless you add some work around fix )
2. if you see "/", "@" ... ( " ", space is not allowed as connector here) in connector field, you will automatically know default (and,at,&) will no longer works, instead "/", "@" will works.
Step 1.
if you leave this field as blank, following connector will be used as default, and, at, &

Step 2.
and, at, & works the same way, only difference is and, at must have space between street name, while & can have no space.
full-name&full-name

full-name at full-name

Step 3.
full-name at partial-name(2-or-3-letter)

full-name&partial-name(2-or-3-letter)

Step 4.
partial-name at full-name( or partial-name) failed.

partial-name&full-name( or partial-name) failed.

Step 5.
test default connector (and, at, &) against chicago street
https://transparentgov.net/json2tree/esri/server/folder2.html?org=https%3A%2F%2Fgisapps.cityofchicago.org%2Farcgis%2Frest%2Fservices&url=https%3A%2F%2Fgisapps.cityofchicago.org%2Farcgis%2Frest%2Fservices&arcgis_online_token=&timeout=9000&select_folder=10&select_layer=-1&select_folder_text=GeoStreets+%3Csup%3EGeocodeServer%3C%2Fsup%3E&select_layer_text=GeoStreets+%3Csup%3EGeocodeServer%3C%2Fsup%3E

Step 6.
full-name&partial-name(2-or-3-letter)
https://transparentgov.net/json2tree/gateway/feature-layer/geocode-suggest.html?backgroundlayerurl=https%3A%2F%2Fgisapps.cityofchicago.org%2Farcgis%2Frest%2Fservices%2FGeoStreets%2FGeocodeServer&layer=GeoStreets&_center_lat=41.88312043380528&_center_long=-87.65470300349665&_center_zoom=19&panto=0

Step 7.
partial-name(4-letter)&partial-name(3-letter)

Step 8.
space as connector does not work

Step 9.
Very important to know,
'/' is NOT default connector, that means if you want to use it, you will have to define it at here.
( " ", space is not allowed as connector here) in connector field

( " ", space is not allowed as connector here) in connector field
Step 10.
if you see "/",
very important, " ", space char is not allowed as connector in connector field,
you will automatically know default (and,at,&) will no longer works, instead "/", will works.
"and" is no longer work

Step 11.
"&" is no longer work

Step 12.
"at" is no longer work

Step 13.
now, only "/" works, nothing else works.

Step 14.
Step 15.
Step 16.
Step 17.
Step 18.
Step 19.
Step 20.