Thank you for joining this Intel Community.
I am so sorry to inform that Cyclone 10 LP device do not support any external memory interface (EMIF) IP. This also mentioned in C10 LP GPIO UG -https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-10/c10lp-51003.p...
I am not aware of any 3rd party that have the support to this. If you want to use EMIF, my recommendation is switch to Cyclone 10 GX as it support DDR3/DDR3L.
I am so sorry for the inconvenience caused.