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These Dell U2415 displays have the following specifications ( https://www.dell.com/lv/business/p/dell-u2415/pd ):
1920 x 1200 at 60Hz
2 HDMI(MHL) connector
1 Mini DisplayPort
1 DisplayPort (version 1.2)
1 DisplayPort out (MST)
1 Audio Line out (connect your speakers)
5 USB 3.0 ports - Downstream (5 at the back, 1 with battery charging)
1 USB 3.0 port - Upstream
Based on the above I would expect these would work well with the Plugable UD-ULTC4K Triple Display Docking Station ( https://plugable.com/products/ud-ultc4k ) and a 2017 MacBook with Thunderbolt 3/USB-C output ports.
Our USB-C Triple Display docking stations require installing the DisplayLink manager App for macOS 10.5.16->11.2.3 ( https://kb.plugable.com/questions/799275 ), this installation requires administrative permissions on the system. If this is a computer provided by your business I recommend checking with your IT department to verify you have permissions to install the DisplayLink software. Additionally, we recommend our USB-C Triple Display Docking stations for use with office and web browsing software, due to the limited USB 3.0 bandwidth and reduced hardware graphics acceleration available to the DisplayLink software, the two DisplayLink controlled external displays may not perform well for full screen video playback, 2D or 3D graphics applications, video editing software, or some stock trading applications. The single USB-C DisplayPort Alternate Mode display will have full hardware graphics acceleration and will perform similarly to the laptop’s built-in display.
For connecting the displays, I recommend the most used/primary display should be connected to the docking station’s HDMI output port using a standard HDMI to HDMI cable. The second and third display may then be connected using DisplayPort to DisplayPort cables to the full sized DisplayPort input ports on the displays. Please note, these displays also have DisplayPort output ports which are not compatible with this docking station or macOS ( these ports will be non-functional, and do not operate as input ports ).
The docking station can replace an Apple power supply rated up to 65W for most systems, for laptops with higher rated power supplies the docking station will be able to power the computer for light to moderate tasks, however under heavy load the system may discharge the battery. It may be necessary to connect the original power supply if it is rated over 65W.
Please let me know if there is anything else I can do to help, and have a great day!