Wrapping huge equation without template dependencies

I am trying to reproduce this huge equation and have it wrap around like so:

https://arxiv.org/pdf/1907.09842.pdf

(equation (3.18) on page 18 of the pdf file)

Here is what the code looks like from the downloaded latex file:

\begin{multline}G_{(u,v)}^{w,2,1}(t)=-\frac{1}{tp_2}\times \\\dfrac{\mathlarger{\mathlarger{\mathlarger{\sum}}}\limits_{l=0}^r\left(   \splitdfrac{\splitdfrac{z_1^{w+2}(z_2^{w-(v-u)_+-l+1}z_3^{(u-v)_++l}-z_3^{w-(v-u)_+-l+1}z_2^{(u-v)_++l})}                                   {- z_2^{w+2}(z_1^{w-(v-u)_+-l+1}z_3^{(u-v)_++l}-z_3^{w-(v-u)_+-l+1}z_1^{(u-v)_++l})}}{+z_3^{w+2}(z_1^{w-(v-u)_+-l+1}z_2^{(u-v)_++l}-z_2^{w-(v-u)_+-l+1}z_1^{(u-v)_++l})}\right)}{z_1^{w+3}(z_2^{w+2}-z_3^{w+2})-z_2^{w+3}(z_1^{w+2}-z_3^{w+2})+z_3^{w+3}(z_1^{w+2}-z_2^{w+2})}.\label{21final}\end{multline}

I am trying to reproduce this but without the dependencies of needing to use his template. Copying this verbatim will not work. Ideally I would just be able to copy and paste something similar to this and have it work without breaking.

I am using the Overleaf platform.