On Magento 2, Remarkety supports the manufacturer data as an attribute set and not as simple attribute. Please find detailed instructions on how to to set up your manufacturer as an attribute set in M2:
How configure the manufacturer field admin dashboard:
1) In your Magento 2 admin, go to Store->Attribute Set
2) Click on button Add Attribute Set
3)Insert attribute set name (Manufacturer) and click Save
4) In next window, drag and drop from right column "manufacturer" to left column "Groups" and save.
5) Next step, need add options to the attribute set. Go to Store->Attributes->Product
6) Find and click to manufacturer attribute set in opened list
7) In opened tab "Properties" under "Manage Options (Values of Your Attribute)" - you are able to add the manufacturer properties.
8) switch to the tab "Manage Labels" - you can change client side label to manufacturer, for example "Brand".
9) Go to product list, choice product and edit it.
In "Attribute Set" find "Manufacturer" and choice him, after this scroll down this page and search a field "Manufacturer". Select option and save.
10) This a finish result
Now Remarkety/mgconnector plugin can synchronize product manufacturer.
For any additional questions, contact us at firstname.lastname@example.org