Thanks for reaching out to us, I am happy to help answer your question, although I don’t think we have a USB-C graphics adapter that will be fully compatible with this display.
Our USB-C to DisplayPort 1.2 cable ( https://plugable.com/products/usbc-dp ) has been tested with 4K UHD ( 3840x2160 ) displays at 8-bits per color channel with modern MacBook systems and may be our most compatible adapter, however it may not work fully with this display. This display at 5120x1440 with 10-bits per color channel actually requires more bandwidth than either the cable or the MacBook is capable of producing to drive the display at full resolution, refresh rate, and color depth.
Additionally, the MacBook’s Thunderbolt 3 port supports DisplayPort 1.2, while this monitor is designed for DisplayPort 1.4 connectivity. The USB-C to DisplayPort cable can be used to connect this display I cannot guarantee the results will be optimal. For example the refresh rate may be limited to 30Hz, which may provide enough bandwidth to drive the display, however the overall resolution may also be reduced as you are seeing with your current adapter.
The results should be better than the current adapter but may not be optimal. USB-C adapters provide two sets of conductors capable of supporting DisplayPort or USB 3.1 Gen 2 communications. In the case of a multiple function adapter like the one linked above, one lane is used for DisplayPort while the second is used for the USB devices. This limits the 4K output to 30Hz refresh rate and is likely also limiting the resolution of this display. Our USB-C to DisplayPort cable can provide both lanes for DisplayPort signal and can provide for 4K output at 60Hz refresh rate. Depending on how well this display handles scaling and how the MacBook handles the very large resolution this may allow for better support for this display but it will not be 100% compatible.
Based on Samsung’s product page ( I could only find the page in German ) it looks like this display offers a side-by-side picture mode that could be used for a seamless dual screen setup using two graphics adapters ( the current multi-function adapter and a separate USB-C graphics adapter ). Using two connections may be a functional alternative to a single connection with the MacBook pro. I recommend consulting the user manual that came with your display to make sure it supports this feature and what inputs are supported. This may not work if the system identifies both connections as the same display, I cannot be 100% sure as the documentation I can find is in German and I do not trust the translations I have on hand.
I am sorry we do not have a single adapter solution that will work with this display, however it looks like it may be possible to use this display with two connections to the computer in extended desktop mode as a “single extended display”.
Please let me know if this helps, or if you have any additional questions.