The Picture says everything.
Thanks

HI!

Read about STP (Spanning Tree Protocol).
The ALCATEL "LACP" part - that is MLAG and not LACP.
MLAG is not implemented correctly between vendors (each vendor has implemented differently).
if you want each link to work parallel - not blocked by STP - then use the same vendors equipment with MLAG - do not mix them.

So your original question, if you use the simple STP config without "MLAG" on Alcatel, it will work.

The ALCATEL "LACP" part - that is MLAG and not LACP.

I disagree. From Alcatel device point if view the links are in LACP mode. Even if all three devices were by same vendor, the bottom one would have to be configured as LACP peer of the upper pair.
However, both CRS518 have to be aware that they serve as MLAG peers. Here I agree, switches in MLAG pair have to be from same vendor.

To answer question of @Ramalama: yes, in case one of client's LACP links go down, traffic will pass ICCP link. Further more, since LACP client (Alcatel) is unaware of link locations of both servers, it may transmit data towards them via "wrong" link, so traffic may flow via ICCP link even if both LACP links are up&running (I guess that switches, members of MLAG group, are smart enough to use locally attached member of LACP bond to transmit traffic towards LACP "client"). So it is important to dimension ICCP link capacity large enough not to become a bottleneck.